I'm not sure how Ancestry would be able to determine whether someone was still living.
It would be nice to have a pop-up on a person that you would have to check living/deceased before info would show when uploading a GEDCOM. That would correct any errors/bugs.
I've found that in most cases when someone is notified that they have info on a living person showing, they immediately correct it. And with a simple google search, anyone can find a whole lot more info. than any tree would give them.
for instance: does this mean anything to you - OSU - Long driveway - 4349 - nearby sportsfield - V.L.S - Cipher - 384 (I don't mean anything by this, just to show how easy info is to find)